This invention is in the field of background signal subtractors using CCD principles.
In many applications it is desirable to delete the DC components of an applied signal, while passing AC signals which have encoded thereon the information to be processed. For example, in imaging systems the DC background signal comprises a large portion of the output signal from the imaging sensor while the useful imaging information is contained in the relatively small, high frequency, portion of the sensor's output signal. In such applications, economy and efficiency of signal processing may be realized by removing the background signal during an early stage of the signal processing operations.
Background subtractors in general are known in the art, such is for example, those which include AC couplers that make use of capacitors and the like. However, the prior art does not include CCD type background subtractors for transferring the AC portion of a signal which may contain DC components; and as compared to CCD devices, commonly used background subtractors are bulky, heavy and expensive. Also, conventional background subtractors or capacitors have the disadvantage of being limited to a fixed or predetermined transfer characteristics.